EP 0 113 073 A1 describes a housing unit with a housing part that accommodates an electric circuit, is protected from moisture by a membrane, and is sealingly closed by a cover serving for the mechanical protection of the membrane. For the purpose of providing a pressure balance in the housing, and to be able to thereby react to temperature changes and/or changes in the external pressure, the cover is provided with a ventilation bore. A housing unit of such design has the drawback that the membrane comes loose during a subsequent process of fitting the cover, for example, by ultrasonic welding, and that the electrical components are thus inevitably again exposed to moisture.